This invention relates to the production of cooling towers. It has particular application to the production of cooling towers formed from annular reinforced shells of a desired curvature and made of reinforced concrete, sections of which are accessible by means of a ladder or a climable or movable shell. The invention is directly related to a process for the production of a cooling tower, as well as the cooling tower itself, and a reinforcing element for use in the process and the tower.
Cooling towers are used for recooling the cooling water of high-performance steam power plants. In "natural circulation" cooling towers, cooling air, because of a "chimney effect" , flows upwardly through the tower. At a specified height, the cooling air is returned into the tower and cooled, by use of a wet coolant such as cooling water which is sprayed into the air or by use of a dry coolant used in a closed-circuit network.
Known cooling towers typcially take the form of a body of rotation. Natural draft cooling towers may take the form of a single-shell rotation hyperboloid, whose waist is in the upper third section of the tower.
Cooling towers made of reinforced concrete usually carry their load by the aid of a supporting framework and a suitable foundation adapted to ground conditions. The shell of the tower is usually erected on the site, capable of withstanding all loads and stresses that occur. Because the main stresses that occur are from the weight of the tower and from wind forces, the tower's ability to withstand buckling and vibration is of major importance.
Because of the steadily increasing performance of modern steam power plants, the need for cooling the air coolant is increasing. Whereas present day cooling towers generally have a maximum height of 170 meters and a maximum diameter of about 120 meters, future heights of 200 meters and base diameters of upwards of 150 meters are envisioned.
With existing cooling towers, the wall thickness of the shells in the waist portion is in the order of 16 to 18 centimeters. In the case of still larger cooling towers, in order to obtain adequate stability of the shell, it has been suggested that the shell be stiffened by horizontal stiffening rings. Because of constructional difficulties and high costs, an installation with horizontal stiffening rings has not been found to be practical in the past.
Accordingly, one of the main purposes of the invention is to create a process for producing a cooling tower and a cooling tower itself and a preformed reinforcing element useful in such production and tower. The towers to which the invention is directed are typically annularly reinforced shells of a desired meridian form, and the invention involves a relatively simple and inexpensive installation of reinforcing rings in the shells of such towers.
These objects are achieved in the present invention by the use of a plurality of plate-like reinforcing elements suspended from the shell in at least one horizontal plane by suspension elements connected to suspension locations on the shell above the plane, and preferably within a plurality of horizontal planes, with the reinforcing elements in each plane abutting and joined one to another and joined to the shell of the tower at spaced points thereon.
In accordance with a preferred embodiment of the invention, the shell of the cooling tower includes spaced-apart recesses in the form of slits passing partly or completely through the shell. The plate-like reinforcing elements are connected together and to the shell by the application of a suitable reinforcing material, such as concrete, which is bonded to the reinforcing elements, joining them one to another, and also filling the recesses so as to join the reinforcing elements to the shell.
The plate-like reinforcing elements useful in this invention are advantageously preformed with a middle solid region having a central channel therein which communicates with trough-like ends for receiving a suitable reinforcing material, such as concrete. That reinforcing material bonds to the reinforcing element and is used to join one element to another and the elements to the shell of the tower. The trough-like ends of the reinforcing elements thus constitute filigree plates integral with the middle solid region of the reinforcing element. The outer edge of that reinforcing element is advantageously bent upwardly; the inner edge of the reinforcing element adjacent to the tower shell includes a projection provided with a sealing element to produce a seal between the adjacent recess in the tower shell and the reinforcing element, to prevent the leakage of reinforcing material when that material is applied to the central channel and trough-like ends of the reinforcing element to join adjacent reinforcing elements together and to bond the reinforcing elements to the tower shell.
The preformed reinforcing elements are advantageously all of the same form. The channel referred to in the middle solid region of each element is upwardly open, and may include reinforcing rods therein for the strengthening of the element when the reinforcing material is poured therein. Anchorages are also included in the reinforcing elements used for suspending these elements from the tower. The reinforcing elements may also include other components mounted thereon useful in the cooling operation of the tower.
The reinforcing elements are preferably mounted in place by the use of a crane. The reinforcing elements may also be suspsended by hand from the lowest foothold within the tower itself.
A particular advantage of the invention is in the use of reinforcing elements which define stiffening rings in a cooling tower. The reinforcing elements abut one another, are made of the same general shape, and are only intermittently connected together and to the tower shell by suitable material, such as concrete. Because the reinforcing elements are suspended from the shell of the cooling tower, it is possible to complete the fabrication and installation of the stiffening rings in the tower independently of the building of the tower structure itself, thereby causing no delay in the tower construction.
The invention will be more completely understood by reference to the following detailed description.